1. Microbiology
Bacteria and Viruses

2. Germ Theory Proposed by Scientist: Luis Pasteur.
Disease is caused by microscopic organisms that invade the body called pathogens (germs).
Bacterial Pathogens (strep throat)
Viral Pathogens (flu)
Eukaryotic Pathogens (malaria)
Fungal Pathogens (athletes foot)

3. Viruses
Classification: None

4. Viruses Viruses are not alive.
No cells
They do not use energy like living things
Cannot reproduce without a host cell
Consist of a protein coat and a piece of either DNA or RNA
They exist only to infect and kill cells

5. Virus Types
All viruses function by injecting their nucleic acid into a host cell and taking over to create new viruses.

6. Lytic Viruses (Ex: Ebola)
Immediate takeover of the cell
Present in virulent (fast) viruses
1. Attach to cell
2. Insert viral DNA into host cell
3. Replicate viral DNA using host cell
4. Assemble new viruses
5. Destroy host cell to release new viruses
End product is more viruses and a dead cell

7. Lysogenic Cycle (Ex: HIV)
Delayed virus cycle; enter the host nucleus and lie dormant for a while
First two steps are the same as lytic
3. Insert viral DNA into host DNA
4. Viral DNA is replicated when host cell divides
5. Virus enters the lytic cycle at any time to kill the cell
*Can be manipulated for gene therapy by replacing viral DNA with a desired gene

8. Virus Cycles

9. DNA or RNA? Viruses based on DNA have no problem invading cells
Polio
Viruses based on RNA (called Retroviruses) have to use a protein called reverse transcriptase to turn their RNA into DNA before they can take over the cell.
Mutate A LOT. Evolve/Change rapidly
Flu

10. Fighting Viruses
Because viruses actually hide inside the cells, it is very hard to treat them with medication
Most viruses are killed by the immune system without meds
The best fight against viruses is prevention. Vaccines can be given BEFORE a person is sick to train them immune system to fight the virus
Since viruses can only survive inside a host, it is important that EVERYONE get vaccinated. If no one can catch the disease, then the disease will be gone forever.
Antibiotics do NOT work against viruses because they cannot penetrate the human cell to reach the virus. Antibiotics only kill bacteria.

11. Bacteria Classification Domain: Archae or Eubacteria Kingdom: Monera
Cell type: single-celled prokaryotes
Feeding: some autotrophic, some heterotrophic
Reproduction: mostly asexual by binary fission; occasional sexual reproduction for genetic variability

12. Domain: Archaebacteria
Primitive bacteria that live in harsh environments.
3 types
Methanogens
Live without oxygen
Extreme halophiles
Live in extreme salt conditions
Thermoacidophiles
Love high temperatures and/or extremely acidic pH

13. Eubacteria
Modern Bacteria classified by shape and reaction to Gram stain
Bacilli: rod
Spirilla: spiral
Cocci: round
Diplo: paired
Strepto: chains
Staphylo: clusters
Gram Stain
Positive: purple
Negative: red

14. BACTERIA

15. Good Bacteria help you! Non-pathogenic bacteria are helpful
Nitrogen fixing bacteria put fertilizer (nitrogen) into the soil for plants
Gut bacteria help humans digest food
Bacteria in the soil helps to decompose and break down waste in the environment

16. Pathogenic Bacteria make you sick!
Antibiotics- medicine for treating diseases caused by bacteria
Interfere with bacterial cell walls
Must be taken as directed
Not effective against viruses

17. Antibiotic Resistance
Caused by using antibiotics too much or incorrectly
Bacteria evolve (by natural selection) to resist the meds
New methods or different antibiotics must be used.